1. Field of the Invention
The present invention relates to electrical systems, and more particularly to a DC to DC converter for an electrical power system.
2. Description of the Related Art
Electric systems used in complex environments such as aerospace systems, more electric aircraft systems, industrial environments, vehicles, etc., include a large number of electric systems and modules. During operation of complex environments, various electric systems and modules may need to be connected to electric power, disconnected from electric power, maintained in a powered-up state, etc., at various times. Moreover, various electric systems and modules in a complex environment may require amounts and type of electrical power specific to each system/module. The power levels required by various parts of the complex environment may also depend on the operational stage of the environment. For example, different levels of power may be needed during the start-up of main engines or auxiliary engine, during continuous operation, or during a battery recharge, in a complex environment such as an aircraft.
On present aircraft systems, three distinct sets of hardware are needed to start an auxiliary power unit (APU) or an engine, and supply the main DC power, such as, for example 28 Vdc power. The three distinct sets of hardware are an AC/DC and DC/AC converter system for starting the APU or engine, a Transformer Rectifier Unit (TRU) or Regulated Transformer Rectifier Unit (RTRU) for the supply of the main DC power, such as 28 Vdc main power, and a battery charger for charging a battery. The large number of units used to provide main DC power and engine start power, negatively impact the reliability of the aircraft, as failure or malfunction of one of the units will affect the power availability and the start procedures. Moreover, the large number of units leads to weight, volume, and cost increases for the aircraft.
Disclosed embodiments of this application address these and other issues by utilizing a multi-functional DC/DC converter that is used as a main DC supply source and as a battery charger when operating in a forward direction, and as a battery power converter to supply power for a starting APU converter, when operating in a reverse direction. The multi-functional DC/DC converter replaces multiple units: the TRU or RTRU, and the battery charger. An aerospace electrical power DC subsystem using the multi-functional DC/DC converter to start an APU or engine, and recharge a battery, leads to significant weight, volume and cost savings, and provides more reliable power functions for an aircraft.